关键词: 重复压裂, 应力转向, 流-固耦合, 有限元

Abstract: The refracturing technology has become an important means to develop the potential of old wells and stabilize or increase the production in oil field, while the reorientation mechanism and fracturing time are the key issues of restraining the stimulation effects of refracturing. This article makes the secondary development of ABAQUS finite element software platform, considers the dynamic evolution of rock porosity and permeability with the volumetric strain, achieves the overall coupling of fluid pressure change and physical property parameters, and makes the fluid-solid coupling analysis of reorientation mechanism of refracturing. The results show that stress reorientation phenomenon is common; the impact range of artificial fracture on the stress is limited which is not enough to form reorientation fracture; and the change of pore pressure is the major factor affecting stress direction; with the continuing progress of production, formation pressure and pore volume decrease, the change of volumetric strain of rock becomes slow, which makes the permeability decreases to a stable value; and the distance of stress reorientation increases and eventually turns to be stable finally; the greater stress differences, the more difficult the reorientation fracture forms because of little stress reorientation distance. This article realizes the visual depiction of stress reorientation in the condition of fluid-solid coupling; and the visual simulation is benefit for guiding the application and implementation of refracturing.

Key words: refracturing, stress reorientation, fluid-solid coupling, finite elements